The Journal of Japanese Society of Stomatognathic Function
Online ISSN : 1883-986X
Print ISSN : 1340-9085
ISSN-L : 1340-9085
A Hypotheses about Mechanism of Tinnitus without Hearing Loss in Temporomandibular Disorders
Ougi SatoToshihiko Matsumoto
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2007 Volume 13 Issue 2 Pages 103-114


A hypotheses about mechanism of tinnitus without hearing loss in temporomandibular disorders was examined by kinetic analysis of temporomandibuler joint as follows: (1) Disc displacement and disc deformation and also joint effusion in temporomandibular joint were examined by using magnetic resonance imaging, (2) Condylar positions were measured on radiographs by using the standardized axial projection and Schuller's projection. (3) Terminal hinge axis point located by using hinge locator (Almore Co.), it was X-rayed and transferred on standardized radiograph and measured the position precisely, (4) Direction and distance of condyle shift at a time of occurrence before and after occlusal treatment were analyzed three-dimensionally on articulator. Furthermore, neuro-otological examinations were done as follows: (5) Activities of the outer hair cells in cochlea were evaluated by DPOAE (distortion-product otoacoustic emission) using GSI-60 system (Grason-Stadler Co.) . And (6) Responses on efferent neural pathway throughout brainstem were examined with SR (auditory stapedial reflex in ipsi-lateral-stimuli) by using GSI-33 middle ear analyzer (Grason-Stadler Co.) . And also, (7) Functions of middle ear transmission system were evalued by TM (tympanometry) using impedance meter MA-4000 (Morita Co.), it were proved as the impedance on tympanic membrane (IMP) and peak pressure in middle ear cavity (PRS) . Those data were gathered from the twenty-five patients (female, 2lto 62 years old), they were classified into two groups by means of the presence (OMS) and/or absence (TMD) of tinnitus, and were analyzed by X2-test and Mann-Whitney U-test for comparing between these two groups.
We obtained the following results, the differences in group OMS comparing with group TMD are significantly noted as follows: (1) Relative frequency of disc deformation, (2) Mesio-distal distance of terminal hinge axis point located on standardized radiograph, (3) Vector Lat/Sag in condyle shift at disorder joint side, (4) Reflex threshold in ear at disorder joint side, (5) Reflex latency L1 and (6) middle ear pressure in ear at opposite side. However, (7) any difference of the activities of outer hair cells in cochlea weren't noted. From these results, a worthy finding of the above mentioned study is on the difference of reflex threshold, which was significantly noted as unilateral disorder at one side, but not on both side.
Referring to these results on neural pathway in stapedial reflex, the valuable consideration is the torsion of condyle capsule stimulates trigeminal ganglion which sends projections to the superior olivary complex.

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